I would imagine that background music in a psychiatric hospital could soothe agitation and alleviate sadness in a patient, for a while anyhow. It could also help provide a calm environment amongst the chaos that pervades.
I heard about someone that recruited others to join them and reported that being involved with music gave them pleasure and relaxed them. They wrote songs communally and felt that they were achieving something positive. They went as far as producing CD’s (with help of course) and when playing them to friends and family, it gave them a sense of achievement and satisfaction.
Some of the subjects chosen were world peace, the environment, living with mental illness, coping with it and they also stressed that working together was preferable to doing the same thing alone. A great idea.